The present invention relates to the field of medicine, and more particularly, to the field of bone grafting. The invention has particular utility in connection with the removal and collection of bone from the surface of one or more donor sites, and the preparation and placement of the autogenous bone material at a second location in the same patient., e.g. for use in grafting bone to osseous deficiencies, such as periodontal and dentoalveolar defects, bone deficiencies around dental implants, and numerous orthopedic applications that require bone grafting, and will be described in connection with such utility, although other utilities are contemplated.
Many reconstructive procedures used in medicine and dentistry involve the manipulation and healing of bones. Such procedures may involve changes in the position, orientation, shape and size of skeletal structures. A problem that is commonly encountered during such procedures is a lack of bone graft material. Bone graft material may be used in many applications, such as to fill between sections of bone that have been repositioned, to change surface geometry, or to add bone to an area that is deficient, such as in conjunction with joint fusion, bone cyst site repair, periodontal surgery or dental implants in a patient""s jaw.
Harvesting of small bone grafts from intraoral sites has been a common practice in periodontal surgery to restore bone defects around teeth. In the case of dental implant surgery, bone grafts may be needed to augment atrophic alveolar ridges of the maxilla and/or mandible and the sinus floor to increase the dimension of these bone sites to accommodate and totally cover the endosseous portion of implant fixtures. Bone grafts also are used in conjunction with guided tissue regeneration, a technique that uses a membrane to isolate hard tissue from soft tissue sites and potentiate hard tissue healing.
It is often difficult to harvest adequate amounts of autogenous bone from intraoral sites. Therefore, clinicians often rely on non-autogenous sources of graft material, such as bone from cadaver sources (homologous or allogeneic grafts), animal sources (heterogenous or xenogeneic grafts), or synthetic (alloplastic) bone substitutes. However, healing of non-autogenous material grafts is not as extensive or predictable as healing of autogenous bone obtained directly from the patient; plus the additional cost of such non-autogenous graft materials which can be significant. Autogenous bone is widely known and accepted as the xe2x80x9cgold standard.xe2x80x9d
Clinicians use several techniques to remove bone for grafting for intraoral procedures. In one such technique a rotary instrument, such as a side cutting burr or trephine, is used to remove a piece or section of cortical bone from a local intraoral site in the maxilla or mandible. The cortical bone is often morsalized into a particulate form, either manually with a rongeur like instrument or in a bone mill. The resulting particulate bone is then positioned and packed into the osseous defect around the teeth or implant.
Another technique is to collect bone dust generated by twist drills or taps used to prepare sites for implant placement. Suction devices with filters have been fabricated and manufactured to collect the bone dust from rotary instruments. This bone is then combined with blood to form an osseous coagulum. However, twist drills tend to generate significant heat which causes some necrosis and denatures proteins. While the site may be irrigated to cool the drill bit, much of the bone material may be lost in the irrigating fluid. Saws, burrs and bone mills also may be used for harvesting and/or preparing bone material for grafting; however, the resulting bone material is either quite powdery or block-like particles with pointed or sharp edges with low aspect ratio. Such materials tend to consolidate with minimal porosity. Robinson, R. E. xe2x80x9cOsseous Coagulum for Bone Inductionxe2x80x9d, J. Periodontology 40:503(1969). See Hutchinson, R A xe2x80x9cUtilization of an Osseous Coagulum Collection Filterxe2x80x9d, J. Periodontology 44:668(1973). See also Goldman, et al, xe2x80x9cPeriodontal Therapyxe2x80x9d, pp 994-1005, C. V. Mosby Co., (1980); and Haggarty, et al., xe2x80x9cAutogeneous Bone Grafts: A Revolution in the Treatment of Vertical Bone Defectsxe2x80x9d, J. Periodontology 42:626(1971). While such techniques are widely used by clinicians, such techniques have limitations, since sites for harvesting sections of intraoral bone are limited in number and extent because of limited intraoral access, proximity to tooth roots, nerve structures and sinus cavities, and thin plates of bone.
Surgeons also employ various hand-driven devices such as rasps, reamers, files, rongers, gouges, chisels and osteotomes to cut and harvest bone. However, such hand-held devices are inefficient for harvesting bone for grafting applications, and normally produce powder-like particles. Additionally, harvesting bone using chisels or the like may be hazardous.
When larger amounts of bone are needed for major reconstructive procedures, sites such as the hip (anterior or posterior ilium), tibia, ribs, or the calvarium often are used. However, using such sources necessitates a second surgical site, which may involve more morbidity and require postoperative hospitalization, and thus is less amenable, e.g. in the case of an out-patient dental procedure.
Various surgical devices have been proposed and/or are in use to harvest bone marrow samples for biopsy, or devices such as rongeurs or bone cutters or punches to remove sections or convex edges of bone. Surgical devices also are in use in arthroscopy and endoscopy for cutting or drilling bone or tissue and removing the tissue fragments. Ultrasonic devices also are in use to cut bone; however, such devices require the removal of the irrigant and debris liberated by the apparatus. Each of these methods and/or devices, however, suffers from one or more deficiencies as applied to the collection of bone for grafting.
U.S. Pat. Nos. 5,403,317 and 5,269,785 to Bonutti show a method and apparatus for the percutaneous cutting and removal of tissue fragments from human. The Bonutti device removes the tissue fragments by suction, where it can be collected and then placed elsewhere in the patient from where originally obtained. Bonutti employs a flexible drill, and suction to remove the debris to an externally placed collection reservoir, where it is compressed before being replaced into the patient.
U.S. Pat. No. 2,526,662 to Hipps discloses a bone meal extractor apparatus for mechanically removing bone meal from a donor bone site through a small percutaneous site using a drill. The drill shavings, which comprise primarily sub-surface bone, are then evacuated into an open cut that the drill passes through, for collection.
U.S. Pat. No. 4,798,213 to Doppelt teaches a device for obtaining a bone biopsy for diagnosis of various bone diseases. The Doppelt device is intended to remove a core of bone using a tubular drill, while maintaining the architecture of the tissue. The sample is obtained from the marrow space and not intended for re-implantation.
U.S. Pat. No. 5,133,359 to Kedem shows a hard tissue biopsy instrument in which samples are taken using a rotatably driven hollow needle.
U.S. Pat. No. 4,366,822 to Altshuler discloses a method and apparatus for bone marrow cell separation and analysis. The Altshuler apparatus collects bone marrow cells in a filtration chamber on a filter interposed between a needle directed into the bone marrow site and an aspirator or vacuum source, i.e. using negative pressure to withdrawal marrow cells through a needle.
U.S. Pat. No. 5,052,411 to Schoolman teaches, a vacuum barrier attachment for shielding the operator of a medical tool from harmful aerosols and blood, etc. created by drilling, sawing types of actions, etc. The Schoolman device requires vacuum and is not intended for harvesting tissue for re-implantation.
U.S. Pat. No. 4,722,338 to Wright et al discloses a device instrument for removing bone which uses a shearing action similar to a rongeur to cut bone, with means for collecting fragments of bone as they are removed. The Wright et al device reportedly is used mainly for the removal of projections or edges of bone using a shearing mechanism without the intent of harvesting the bone for grafting.
U.S. Pat. No. 4,994,024 to Falk teaches an arthroscopy hook-clippers device that allows the unobstructed removal of tissue or bone with removal of the fragments by suction. The Falk device is intended for arthroscopy applications and for the removal of projections of tissue or bone and not specifically for the harvest of tissue for grafting.
Yet other prior art devices are disclosed in U.S. Pat. No. 4,466,429 to Loscher et al and U.S. Pat. No. 4,844,064 to Thimsen et al.
In our U.S. Pat. No. 5,683,406, we disclose a hand-held surgical instrument for cutting, removal and storage of bone surface shavings for use as atogenous bone grafts which is an improvement over the aforesaid prior art methods and apparatus. More particularly, as described in our aforesaid parent, there is provided an instrument (which is now available commercially, as the mx-grafter(trademark) bone grafting system from Maxilon Laboratories, Inc., of Hollis, N.H.) comprised of a blade mounted in a handle for holding and supporting the blade. The blade has a cutting structure adjacent its distal end in the form of a sharpened wedge-shaped loop. The loop""s wedge shaped cross-section is defined proximally by a perpendicular curved aperture through the blade, and distally by a ground relief. The handle includes a hollow space which provides a storage space adjacent the distal end of the blade for receiving harvested bone from the cutting operation. The instrument is designed to be held at an acute angle to the bone, and with minimal downward pressure, drawn across the bone surface to shave and cut and collect bone material. The blade is retractable to allow the clinician access to the harvested material. A plunger is incorporated into the handle to serve both as a locking mechanism to secure the blade and as a means to advance and consolidate the bone in the distal aspect of the instrument. We have found that the instrument of our aforesaid parent applications, when properly used to cut and harvest bone, creates convoluted shavings or ribbons, filaments or sheets of bone material with blood in its intersities, which material has proved to be uniquely superior for use as bone graft material. Typically, the harvested bone has an expanded volume of at least about two fold, typically five to fifteen fold expanded volume. Also, when harvested from living bone, the harvested convoluted bone material also includes copious quantities of blood with a form similar to the trabeculae of cancellous bone. While not wishing to be bound by theory, it is believed that the cut blood vessels of the bone continue to bleed until exposed to air. Thus, as seen in FIG. 5, the one blood vessel 52A exposed to air is not bleeding, while the other blood vessel 52B continues to bleed into the bone shavings where it is drawn out by a wick-like action into the void spaces 54 subtended by the bone shavings. This latter phenomena is quite unexpected since conventionally cut or drilled bones look quite dry. However, when live bone is shaved, blood from coincidentally cut vessels is drawn into the bone interstices by a wick-like action. The resulting harvested bone material has a substantially increased continuous surface area and occupies a substantially greater volume as compared to the donor bone. The resulting open matrix of convoluted bone shavings allows rapid ingrowth of capillaries and bone growth to take place on the shaving surfaces. This process of healing takes place rapidly compared to that of block or conventionally obtained particulate grafts, because pathways for capillaries exist without the need for significant bone resorption.